At two and half acres, Allen Centennial Gardens is small, but it has the botanical diversity of gardens four times its size. You can find 25 distinct spaces, from the dwarf conifer garden to the small fruits garden, each with little curving paths that let you get up close to the nature.
This public garden is tucked away on the University of Wisconsin campus. It's free (donation-funded) and open year-round. Most usefully, the picaresque garden serves as outdoor classroom. Going beyond simply labeling the plant life, Allen demonstrates different gardening techniques, from lasagna-style layering to Czech crevice rock gardens.
If you go this year, you can catch a whimsical "paint brush" art installation. All in all, Allen Centennial Gardens is a charming and educational place to take a stroll.